A playback apparatus for playing back a content having been stored in an internal HDD (Hard Disc Drive) embedded in a BD (Blu-ray Disc) recorder, a DVD (Digital Versatile Disc) recorder and so on has a function to display a list of titles of stored contents on a display screen like a television and display, to a user, what kinds of contents it stores.
The user selects a content that he/she desires to view from the displayed list of titles, and a playback apparatus plays back the selected content. At this time, a restriction on playback like a parental lock is sometimes put on the content. Accordingly, there are contents which can be played back only after a password input by the user is authenticated.
Patent Literature 1 discloses a playback unlock apparatus that can remove a viewing restriction by a user inputting a password into a BD recorder using a remote control provided with a digital television and the like, and play back a content.